Fetch provides a generic definition of Request and Response objects (and other things involved with network requests). This will allow them to be used wherever they are needed in the future, whether it’s for service workers, Cache API and other similar things that handle or modify requests and responses, or any kind of use case that might require you to generate your own responses programmatically. [project site]

Going Further

If you need to do more complicated calls, then take a look into the Fetch docs. Many of the properties and functions are already available in the Fable bindings. If not please create an issue at the Fable issue tracker and I will try to add it.